Presses for treating material in the form of sheets



H. BOBST v 2,949,297 PRESSES FOR TREATING MATERIAL IN THE FORM OF SHEETSAug. V16 1960 Filed April 3. 1957 PRESSEQ FOR TREATHIG MATERIAL IN THEFORM SHEETS Henri Bobst, Lausanne, Switzerland, assignor to J. Bobst andSon S.A., Lausanne, Switzerland, a corporation of Switzerland Filed Apr.'3, 1957, Ser. No. 650,361

Claims priority, application Switzerland Apr. 16, 1956 8 Claims. (Cl.271-45) The present invention'relates to presses for treating materialin the form of sheets such as, for example, sheets of cardboard orpaper, with the object of cutting or shaping the same.

According to the present invention there is provided a press for thetreatment of material in the form of sheets conveyed by a pair ofendless chains which are moved and stopped alternately, the said chainspassing over a pair of wheels whose shaft is keyed in movable blockswhich are subjected to an action intended to tension the springs.Further, means are provided for varying the tension applied to theconveyor chains synchronously with the operations of the press, in sucha way that the said tension is less during the phases when the chainsare stopped than between said phases.

For a better understanding of the invention, a preferrcd embodimentthereof will now be described with reference to the accompanyingdrawings, in which:

Fig. 1 diagrammatically illustrates a press in which might be embodiedfeatures of the invention; and

Fig. 2 illustrates a detail of the invention.

Fig. 1 of the accompanying drawing shows a press wherein sheets areconveyed by means of a pair of endless chains which carry intermediatebars provided with grippers.

1 is the frame of the said press, 2 an upper plate and 3 the lowerplate. It will be assumed that the lower plate 3 is lifted and loweredalternately in order to cut out or form the sheets which the endlesschains 4 convey by means of spaced gripper bars 5 which are carriedbetween the chains. To this end, the said chains are stopped each timethat a sheet is introduced into a gripper bar, while another sheet issimultaneously treated between the two plates.

The chains 4 are guided principally by the pairs of chain wheels 6 and7, and if necessary by other wheels, rollers or appropriate members (notshown).

-It will be understood that there are a plurality of chains and chainwheels, and that they are arranged in pairs whose two components aresuperposed and thus shown as only one element in the drawings.

Since the gripper bars 5 must take up a well defined position both atthe instant when the sheet is taken up and at the instant when a sheetis being treated, pairs of stops are provided at 8 and 9 against which amechanism, driven synchronously with the operations of the press,momentarily pushes the gripper bars, either displacing them in theirnormal direction of conveyance (in the illustrated example, in thedirection of the arrow) or in the opposite direction, depending on thetype of mechanism envisaged.

This possibility of imparting to two gripper bars an independentmovement in order to bring them into contact with stops makes itnecessary to allow the chains a certain flexibility so as to allowsections of the chain between the two stops or otherwise to bede-tensioned momentarily.

Up to the present time, this has been provided for, for

Patented Aug. 16, 1960 example, by keying the shaft of the pair ofwheels 7 in blocks 10 which are movable in slideways, and which arereturned by springs 11 in the direction causing the chains to betensioned.

However, the force which these springs exert must not impede theeflicient operation of the truing means for determining the position ofthe two gripper bars each time the chains are halted. Therefore thevalue of the said force is limited.

Now, in large presses, the whole assembly of chains and bars is ofsubstantial size, and the inertia effects resulting therein makethemselves felt on all the members guiding the chains, both at theinstant when they are immobilized and at the instant when they resumetravelling.

If the springs 11 are too weak, this would inevitably lead toirregularities in chain tension and in the carrying of the gripper bars,and this would lead to the power of the tensioning elements beingincreased beyond the limit defined thereinbefore.

The present invention solves the problem which is posed by providingmeans for modifying the tensile stress applied to the conveying chainssynchronously with the operations of the press, in such a manner thatthis tension is less during the periods when chains are immobilized thanbetween such periods.

In Fig. 2, 7 again designates the wheels conveying the chains 4, and theblocks 10 on the wheels shaft 12 are capable of moving back and forth inslideways 13. Elastic members, which are not illustrated in thedrawings, act in the manner of the springs 11 of Fig. l, tensioning thechains 4 by applying a tr-active force to the wheels 7 in the directionof the arrow 14.

This tractive force is suificient to insure regular ten sioning of thechains in the condition of rest, while the operations necessary for thedisplacement of the gripper bars in order to bear against the stopsoblige certain portions of the chains to be detensioned.

Auxiliary springs or resilient devices 16 are adapted to exert anadditional pressure, in the same direction as the tractive force 14, onthe blocks 10 of the shaft 12, through the intermediary of straps orsplit rings 15 which do not rotate since the chain wheels are freelyrotatable on their shaft. This arrangement is identical at both ends ofthe shaft 12.

Each spring 16 is wound about a rod 17 of an eccentric 18 and is heldunder a certain appropriate tension between s-houlders or washers 2d and2%, the position of the latter washer being adjustable by action of thenuts 21. The said rod has a head 22 capable of sliding in a radialrecess in the strap 15.

Rotation of the pin 19 of the eccentric brings the spring 16 into actionand out of action alternately. Fig. 2 shows the spring in the inactiveposition.

It should be noted, however, that when the spring 16 is in thisinoperative position. there is a slight clearance 23 between the washer2.0 and the strap 15, the eflect of which is to delay the instant whenit is applied against the latter.

Thus, during one complete rotation of the eccentric 19,- there is a deadperiod or inactive period during which the spring 16 is displacedwithout having any effect, due to the clearance 23, and an operativeperiod during which it bears against the strap 15 by means of the washer20. Being already under tension between the washers 20' and 20-, spring15 develops over a very 5 short distance of travel a pressure which isinstantastrap 15 preferably just before the chains are set in motion,during the movement of the latter and at the instant they areimmobilized, while the auxiliary tension of the spring 16 is relaxedimmediately after stoppage of the chains and during the said stoppage,to be produced again just before they are again set in motion.

In order to achieve this result, it is sufficient to connect the pin 19of the eccentric to the main shaft controlling operations of the press,which will insure the desired synchronous working.

In the example described and illustrated, the rod 17 is disposed with acertain inclination relatively to the direction in which the-blockslides. It will be apparent that any other angle, preferably a smallerangle, is possible, and that it would also be possible to cause thesprings 16 to act in the direction of the arrow 14.

It will also be apparent that instead of causing the springs 16 to betensioned by eccentrics, other mechanisms could be used for thispurpose, for example levers and cams, and it would also be possible touse draw springs instead of compression springs.

Referring to Fig. 1, it is also apparent that the tension of the alreadyexisting springs 11 could also be modified periodically.

Finally, it would also be possible to tension the chains by partly orwholly hydraulic means, the pressure of the fluid being variedappropriately.

What I claim is:

l. A press for treating sheet material and having a feeding zone and anoperational zone comprising an endless conveyor passing through saidzones, wheels supporting said conveyor, gripper means on said conveyorfor engaging a sheet at the feeding zone and transporting the sheet tothe operational zone, stops positioned adjacent the conveyor to engagethe gripper means and properly position the same relative to said zones,resilient means coupled to one of the wheels for displacing the same forplacing the conveyor under tension to enable a proper positioning of thegripper means, and control means coupled to the resilient means forselectively controlling the tensioning provided thereby to enable atruing of the positioning of the gripper means, said press furthercomprising a slideway supporting said one wheel for displacement totension the conveyor, said resilient means engaging the latter saidwheel to displace the same in the slideway; said control means engagingthe resilient means and providing a force supplementing the forcesprovided by the resilient means.

2. A press for treating sheet material and having a feeding zone and anoperational zone comprising an endless conveyor passing through saidzones, Wheels supporting said conveyor, gripper means on said conveyorfor engaging a sheet at the feeding zone and transporting the sheet tothe operational zone, stops positioned adjacent the conveyor to engagethe gripper means and properly position the same relative to said zones,resilient means coupled to one of the wheels for displacing the same forplacing the conveyor under tensio'nto enable a proper positioning of thegripper means, and control means coupled to the resilient means forselectively controlling the tensioning provided thereby to enable atruing of the positioning of the gripper means, said resilient andcontrol means providing forces in sub V 4 stantially the same direction,the force of said control means being controllably variable.

3. A press for treating sheet material and having a feeding zone and anoperational zone comprising an endless conveyor passing through saidzones, wheels supporting said conveyor, gripper means on said conveyorfor engaging a sheet at the feeding zone and transporting the sheet tothe operational zone, stops positioned adjacent the conveyor to engagethe gripper means and properly position the same relative to said zones,resilient means coupled to one of the wheels for displacing the same forplacing the conveyor under tension to enable a proper positioning of thegripper means, and control means coupled to the resilient means forselectively controlling the tensioning provided thereby to enable atruing of the positioning of the gripper means, the resilient andcontrol means being coupled for controlling the operation of theresilient means.

4. In a press having a conveyor driven by a wheel resiliently supportedfor tensioning the conveyor, a control comprising a resilient device forengaging the wheel to provide at least a portion of the tension on theconveyor, and means coupled to the resilient device for controlling theengagement thereof with the Wheel.

5. In a press having power means for operating the press, gripper meanson the conveyor for gripping said materials, stops positioned adjacentsaid conveyor to engage said gripper means and properly position thesame in different operation zones, a conveyor for conveying materials tothe press, a Wheel for driving the conveyor, a resilient device forurging the wheel in a predetermined direction intended to continuouslymaintain the conveyor under tension; a control comprising a couplingdevice connected with the wheel and defining a bore, a rod extendinginto the bore in a direction having a major component along saidpredetermined direction, a first shoulder fixed on the rod and spacedfrom the coupling device, a second shoulder loose on the rod adjacentthe coupling device, a spring on the rod between the shoulders forurging the second shoulder against the coupling device, and an eccentriccoupled to the rod for controllably urging the same into the bore forthe controlled de-tensioning of the conveyor due to the urging of thesecond shoulder against the coupling device.

6. A control as claimed in claim 5 comprising a shaft for the wheel;said coupling means being a split ring mounted on the shaft.

7. A control as claimed in claim 5 comprising adjustment means on therod for adjusting the position of the first shoulder to control thetension of said spring.

8. A control as claimed in claim 5 wherein the spring has a lengthwhereby the second shoulder is adapted for being spaced from thecoupling means in at least one position of the eccentric.

References Cited in the file of this patent UNITED STATES PATENTS492,872 Maybach Mar. 7, 1893 733,385 Goldsmith et al. July 14, 19032,254,592 Berkeley Sept. 2, 1941 2,512,084 Bobst June 20, 1950 2,664,757Shaw Jan. 5, 1954

